Abstract:The effect of water toughening and aging treatment on the microstructure and hardness of high manganese steel was studied, the microstructure was analyzed by confocal laser microscopy and X-ray diffraction (XRD), the Vickers hardness was measured by microhardness tester. The results show that the microstructure after water toughening is austenite and a small amount of carbide, when the holding time was short, the carbide dissolved incomplete, with the holding time extended, the carbide completely dissolved, austenite grains grow; Compared with the as-cast structure hardness of HV 461.6, the microstructure hardness after water toughening treatment decreased to HV 229.9. With the increase of aging temperature and the extension of holding time, needle-like carbides will be precipitated at the austenite grain boundary first, then these needle-like carbides will grow into the grain interior, and point-like carbides will be precipitated at the grain boundary; With the increase of aging temperature, the microhardness value increased gradually, and when the microstructure changed obviously, the microhardness value of the sample increased suddenly; When the holding time increased from 1 h to 3 h, the microhardness of the sample mostly increased, but the microhardness of the aging temperature 300 ℃ and 350 ℃ had little difference.